This invention relates to a device for mixing and blending fluids such as paint, lacquer, and varnish, epoxies, drive-way sealants, joint compounds, roof coatings and more particularly to a rotatable disc-like impeller for uniformly mixing fluids and high-viscosity materials into a homogeneous condition.
Many different rotatable impellers have been suggested for the mixing and blending of fluids such as paint, lacquer and varnish. Most of these devices work reasonably well in blending the suspended solids in the liquid.
Quite often it is encountered that certain mixtures are more difficult to blend due to heavier components which tend to settle to the bottom, and escape the mixing vortices created by the rotating impeller blades. Also, it is often experienced that containers in which fluids have been stored for a considerable length of time, have deposits which have settled to the bottom. These bottom deposits are most difficult to raise from the bottom, and even high speed impellers encounter difficulty in providing mixing homogeneity to such liquids.
Impellers are generally designed to provide turbulent vortices within the fluid, which vortices create an upward flow of bottom components.
It has been observed that large molecular weight components, having higher viscosities, often resist this turbulent flow. Thus, even high speed mixing devices have problems with heavy bottom components.
This invention has discovered than an improved blending current could be created within the fluid, by allowing a smoother fluid flow-through to develop between the rotating blades of the mixing impeller. In other words, it has been discovered that a finer blending could occur if the flow stream moved rapidly through, as well as around, the rotating blades.
It has been further discovered that this smoother flow-through provided the blade designer with an additional advantage, wherein the angle of attack between the impeller blades and the fluid could be increased without a substantial increase in rotative driving power.
Increasing the blade angle to 15.degree. without requiring excessive driving horsepower, allows the impeller of the present invention to be mounted upon almost any low-power, household drill.
The present invention also provides the impeller blades to contiguously come into contact with the bottom wall of the container despite the higher blade angle of attack. This improves the ability of the blades to lift stubborn bottom components and force them into the mixing stream. This contiguous contact is achieved by beveling the trailing circumferential edge of each impeller blade, wherein each blade rides over the bottom wall of the container.